LÖVE

How can I check if a body is in contact with others?

Bounding Box collision
Just insert x, y, width, height for each box.
When two boxes intersect the function returns true.

I assume you are talking about Box2D.
There are several ways to do this.
One approach is setting a contact/collision callback and buffering the collision data you get from there.

I would strongly suggest hardon collider.

http://vrld.github.com/HardonCollider/tutorial.html